No circulation in cooling system ( 78 240d )
 

So far I've replaced the waterpump (old one looked fine), checked the belt, topped off coolant, checked thermostat(even tried running with it removed) and I'm still not getting any circulation. Radatior is new and cold to the touch, hoses are all cold and the temp gauge shows it overheating everytime(verified with laser thermostat).

The car didn't start overheating until i added some coolant to the system. It was running fine up until that point. From then on it would overheat, if I drove it long enough it would appear that the coolant would circulate intermitantly I'd be driving with the guage way above 175 then all of a sudden it would drop to 175. Unsure what else I can try before throwing more money at the problem. I know it could be the head gasket, anyone know of anything else I could try?

Check for an internally collapsed hose by chance?
I've seen that on several occasions.

Air lock? Are you getting heat from the heater core? Have you tried burping it? Have you tried adding coolant via the top radiator hose directly into the block?

Doesn't appear to be a collapsed hose, but will double check.

Haven't checked for heat from heater core yet. How would I go about burping it? I haven't tried adding coolant directly to the block yet either. I will try after work and report back.

Point the front of the car uphill--put on ramps if necessary. Run the engine with the heater on full blast until the air lock burps out.

I have ramps, but no hills around me. Doesn't need to be so steep?

Needs to be steep enough to get the air to move to the radiator.

Airlock in the heater core isn't going to stop flow out of engine and through the radiator.

Wonder if theres a wad of scale or sludge blocking the upper / lower outlets?

Reverse flush ?

The point of operating the heater is not to remove air from the heater core. It is to vent air from the head so that coolant can reach the thermostat.

No bypass on the pump then?

Ok.
Learned something.
If he can't elevate it, adapt a garden hose and run it through the core?

My old Midget had a valve on the side of the head but it didn't need to be open to clear the head.

I took the cap off let the car get to operating temp at an incline then filled with coolant to the top. Turned off the car and put the cap on. I attempted to burp it, maybe i'm doing something wrong, but nothing happened. Heat and fan set to max and remain cold while engine temp approaches and exceeds 200.

What color is your coolant? I ask this because you could have a blocked coolant passage in the head somewhere due to rust or other contaminants.

Putting coolant in the radiator doesn't fill up the block, that's why I said you should the block using the upper radiator hose.

It's green, don't see anything wrong with it.

I will try this now.

Careful if the engine is at 200 degrees. Also, you want to burp it with the radiator cap off.

filled up the block from the top hose until it started overflowing then ran the car with the same results :\

Is there any heat in the heater? If not, you have an airlock in the back of the engine. I'd try pulling one of the back heater hoses to see if you get circulation.

no heat, just cool air

That would confirm you have no coolant circulation. I would remove the bleeder line on the water pump and make sure it and the banjo bolts are clear. It sounds like the water pump is still airbound.

If all you did was add coolant and then had these overheat troubles, there must be something internal blocking coolant flow. Especially when you said it got hot, then cooled down.
All these other mechanical things were after you added coolant, right?

Maybe try reverse flush?

Hey, you know what?
Don't some of the coolants gel up if mixed with the wrong type?

At this point I'd be looking to fab up a device to hook a garden hose to a radiator hose and then see how much flow you can get through the block.

I'd also just double check the flow through the radiator. Take the bottom hose off and rotate the top hose to be able to put a garden hose into the top and make sure you've got good flow going through the radiator.

If the block flows well, the radiator flows well, the pump pumps and the thermostat is working (or not there) then it comes down to air.

Correct, issue only started after adding coolant.

This could be it, my father added the coolant before the issues started, not sure what kind all I know is it was 50/50.

Should I just follow this guide?

How to reverse flush « Vehicle Enhancement Labs

Will attempt the flush tonight.

Are there any pdfs of service manuals available for this car around here?

There are probably multiple issues going on here. What's never been explained is why it needed coolant to begin with. Did it overheat? Was it leaking? Did it ever run at the correct temperature once this coolant was added. Was this coolant added via the radiator or the upper radiator hose. When the water pump was changed was there evidence of coolant in the block? Have you loosed any heater hoses to see if coolant is present? Can you see coolant circulating in the radiator with the cap off and the engine running?

My father thought it looked low and took it upon himself to add, was not leaking, nor was it overheating. The car ran at a steady 175 and it took about a day for the issue to crop up. I'm certain the coolant was added via the radiator. I haven't taken a look at the heater hoses yet, will do today. With the cap off the coolant does not appear to be circulating.

remove any high mounted heater hoses from the engine and fill it, if you dont see any movement of coolant anywhere and no signs of bubbling or air, then maybe your waterpump just let go of the impeller blade.

At this point, I'd hook up to the rad hose and reverse flush with water only to start.

Look for the empty can your Dad used.
Something about it gelling if mixed with the older type fluid I think.

I took the hoses off the thermostat housing and filled both the inlet and outlet with gardenhose water until they started overflowing. Next I filled up the radiator hoses as much as I could and put them on. Seems to have fixed my issue.

Still bothering me that I couldn't find the root cause.

Thank you all for the helpful tips!

Root cause was an airlock. These engines are notoriously hard to fill with coolant without causing an airlock. Your airlock was more problematic than most.

My 616s seem to be harder to burp than the 300TD. What I do is raise the front and disconnect the top radiator hose at the radiator like Kerry said but I also disconnect the heater hose, driver side at the firewall, wire it up and add coolant in the radiator hose till it overflows out the wired up heater hose.

Now you got to do it again with antifreeze. :eek: